Problem: $\dfrac{9}{12} - \dfrac{3}{6} = {?}$
Explanation: $ = {\dfrac{9 \times 1}{12 \times 1}} - {\dfrac{3 \times 2}{6 \times 2}} $ $ = {\dfrac{9}{12}} - {\dfrac{6}{12}} $ $ = \dfrac{{9} - {6}}{12} $ $ = \dfrac{3}{12}$